Citing the arrest affidavit, The San Antonio Express-News reported that the child alerted his mother to the alleged sexual assault while Medellin was still in their home on March 28. The mother immediately called police, and both the boy and Medellin were taken to the hospital to undergo a sexual assault examination ― the results of which were released on Wednesday and appeared to confirm the child’s account of the assault, reported WOAI-TV.

The boy’s DNA was found on Medellin’s breast, according to Express-News, adding that “male DNA was also found on her genitals, but the sample was not sufficient enough to make a positive comparison.”

Medellin was arrested on Thursday and is being held on $75,000 bond, reported KENS 5 News. It remains unclear if the woman had a relationship with the boy’s family beyond her babysitter role.

Most victims of child sexual abuse are assaulted by someone they know. According to the Rape, Abuse and Incest National Network, more than 90 percent of child sexual abuse victims know their abuser ― often very well.